Characterization of XLPE MV-size DC Cables by Means of Space Charge Measurements

This paper presents a comparative study between three different types of XLPE MV-size DC cables. Space charge measurements by means of the pulsed electroacoustic (PEA) method are used as a tool for the characterization of the MV-size cables. For the measurements, test conditions were adopted, which resemble the working conditions experienced by the DC cables in the field. In fact, measurements were performed at variable cable load and at different values of the applied voltage. From the experimental results, the main space charge accumulation mechanisms were identified. In particular, hetero-charge accumulation near the electrodes and space charge accumulation in the insulation bulk were observed. On the basis of this information, a prediction of the field enhancement experienced by the cable insulation is presented.